The present invention relates to an axle supporting structure of an industrial vehicle which rotatably supports a center pin of an axle beam between a pair of axle supporting units which are spaced away from each other in a traveling direction of the industrial vehicle, and to the industrial vehicle having the same.
In a counterbalanced forklift truck, its rear axle beam is generally supported in such a manner that the beam is pivotable or swingable in a rolling plane about a center pin for improving the stability of the vehicle when traveling on the surface of a rough ground. The center pin of the rear axle beam is inserted through holes formed in a pair of axle supporting units which are spaced away from each other and located at the front and rear sides of the rear axle beam, thus being rotatably supported by the pair of axle supporting units.
The axle supporting units protrude downward from a rear frame that horizontally extends in the rear of the vehicle frame. Each axle supporting unit is constructed so as to be separable into an upper part and a lower part which cooperate to form a center pin insertion hole when the upper and lower parts are connected to each other. Specifically, each axle supporting unit includes an upper axle supporting member having formed therethrough an upper half of the center pin insertion hole and a lower axle supporting member having formed therethrough a lower half of the center pin insertion hole. The upper axle supporting member is joined to the rear frame by welding while the lower axle supporting member is detachably mounted to the upper axle supporting member by means of bolts or the like.
In order that the vehicle frame supports the rear axle beam, firstly the center pin of the rear axle beam is arranged in the semicircular hole of the upper half of the center pin insertion hole of the upper axle supporting member with the lower axle supporting member of the axle supporting unit detached from the upper axle supporting member. Then the lower axle supporting member is arranged so as to support the lower half of the center pin and fixed to the upper axle supporting member by a bolt. In each center pin insertion hole of the axle supporting units, a bushing is arranged to prevent metal touch between the axle supporting unit and the center pin.
Japanese Unexamined Patent Publication No. 2000-16039 discloses axle supporting unit of the above type. See page 2 and FIG. 1 of the reference. In the reference, however, each upper axle supporting member of the axle supporting units is joined to the rear frame by welding which is troublesome and costly.
Further, in the prior art wherein each upper axle supporting member of the axle supporting units is joined to the rear frame by welding, it is difficult to ensure that the paired center pin insertion holes are positioned in concentric relation to each other. In order to improve the concentricity of the center pin insertion holes of the welded upper axle supporting members, the bushing made of rubber is disposed in the center pin insertion hole. However, since rubber is relatively costly, the cost of the prior art axle supporting structure is increased.
Further, in the prior art structure disclosed in the above reference, the strength at the joints between the upper axle supporting members and the rear frame is not sufficient. That is, it is difficult to ensure a sufficiently high strength in the prior art axle supporting structure.